I don't know about firearms laws there but I do know two things...1) on my first trip to Singapore I recall the big sign,in several languages,at the immigration desk saying "death penalty for drug traffickers".I almost soiled myself and all I had in my possession were my blood pressure meds and 2) the cab driver who picked me up at the airport warned me that there's a law there regarding "insulting the honor" of women and it can land you in prison for a long time.
Also illegal to spit or fail to flush a public toilet, and for many years bubble gum was totally illegal.
They changed that last bit about 5 years ago, I believe.